In order to solve the problems such as air pollution or increase of CO2 emission, development of an electric vehicle such as a pure electric vehicle (EV) using electricity with a driving motor as a driving source without having exhaust gas or a hybrid electric vehicle (HEV) having an engine and a driving motor as a driving source has drawn attention.
Generally, a power system of an electric vehicle is configured by a main battery (a high voltage battery) which supplies driving power of a driving motor, a battery management system (BMS), an auxiliary battery (a low voltage battery) which supplies driving power of other vehicle electric components and a plurality of electric devices.
The electric vehicle includes an inverter and a low voltage DC-DC converter (LDC). The inverter converts a high DC voltage which is generated in the high voltage battery (a main battery) into an AC voltage to control the motor to be driven and LDC converts the high voltage generated in the high voltage battery to output a low voltage and charge the low voltage battery (an auxiliary battery).
Therefore, since the high voltage battery and the low voltage battery are connected to the LDC, a high voltage (+) terminal and a high voltage (−) terminal to which the high voltage battery is connected and a low voltage (+) terminal and a low voltage (−) terminal to which the low voltage battery is connected are provided in the LDC.
In this case, when an operator connects the high voltage battery and the low voltage battery to the LDC, an erroneous connection may occur due to mistake or carelessness of the operator.
As examples of the erroneous connection, the (−) terminal of the high voltage battery is connected to the high voltage (+) terminal and the (+) terminal of the high voltage battery is connected to the high voltage (−) terminal, or the (−) terminal of the low voltage battery is connected to the low voltage (+) terminal and the (+) terminal of the low voltage battery is connected to the low voltage (−) terminal, or the low voltage battery is connected to the high voltage terminal, or the high voltage battery is connected to the low voltage terminal.
As described above, when the battery is erroneously connected, a short-circuit may be generated through a body-diode of an FET and as a result, fatal influence may be applied to a vehicle system.
Accordingly, in order to prevent an accident due to the erroneous connection, in the related art, a method which opens the circuit using a fuse in the event of over-current to stop supplying the power.
According to the method of shutting off the over-current using the fuse of the related art, even though it is possible to shut off the circuit, but since the circuit is mechanically shut off, the vehicle cannot be reactivated and thus cannot be driven before exchanging the converter.
The fuse which is used for the converter is an expensive component and thus lots of cost is spent for post-processing. Further, in recent years, circuit components have been diversified and thus working efficiency is lowered.